In emergency situations most emergency personnel carry a two-way radio for communication, for example with other members of their responding group (e.g., firefighters on a particular truck, from a particular station, or emergency personnel generally on site fighting a fire or providing other assistance). For instance, emergency personnel may also be communicating with members of other groups (e.g., firefighters communicating with paramedics and/or police officers).
Sometimes two-way radios aren't able to transmit messages reliably due to the frequency band being clogged or overrun by too many users competing to utilize the same frequency band at the same time. In such situations, it may be difficult to ascertain the status of an emergency worker, such as whether they are in a room with fire or are under some type of stress (e.g., in a hot environment, injured, trapped, carrying an injured person, etc.). This information may be difficult to receive if the channel for communication is clogged with other users.